Recently, it is known that a high-rise building continues shaking at a low cycle time by a long-period ground motion or a strong wind whose influence is reported. In an elevator, there occurs a phenomenon that a rope such as a main rope, governor rope, or compensation rope has a period close to that of the building shakes to resonate, resulting in that the rope contacts hoistway devices thereby being damaged, or is caught thereby. If the elevator is operated with the rope caught by the hoistway devices, damages may occur in the hoistway devices, causing passengers to be entrapped or developing into a situation requiring a long time restoration.
In order to prevent such situations, an elevator rope sway detection device has been proposed to detect that the elevator rope sways more than a predetermined distance (refer to Patent document 1 or Patent document 2, for example).